Radial flow rotary regenerative heater



July 13, 1965 A. KQVATS 3,194,301

v RADIAL FLOW ROTARY REGENERATIVE HEATER Filed Nov.. 27, 196s -2sheets-sheet 1 l .34 3l 45 INVENTO M A/vopf Kon/A 7.5

32 o 2' BY ,M ma, EZ 4 l z; ATTORNEY July 13, 1955 A. KovATs 3,194,301

RADIAL FLw ROTARY REGENERATIVE HEATER Filed Nov. 27, 1963 2 Sheets-Sheet2 y I @W4 INVENTOR AND/P- Kl/A 7'5' ATTORNEY United States Patent O3,194,301 RADIAL FLOW RUTARY REGENERA'IIVE HEATER Andre Kovats,Livingston, NJ., assigner to Foster Wheeler Corporation, New York, NX.,a corporation of New York Filed Nov. 27, 1963, Ser. No. 326,401 3Claims. (Cl. 16S- 7) This application is a continuation-inpart of U.S.patent application Serial No. 211,325, filed July 20, 1962, nowabandoned.y

This invention relates to preheaters and particularly to radial flowrotary regenerative preheaters.

In preheaters which are most commonly used for heating combustion airfor use in a furnace with the flue gases from the furnace, it has beenstandard practice for the hot and cold fluids to be fed in and out of arotating matrix to transfer heat from the hot tluid to the cold fluid. Acrossow design is most commonly used in which the cold fluid is passedacross one side of the matrix through a straight duct in one directionwhile the hot huid is passed in the opposite direction through astraight duct across the other side of the matrix. As the matrix rotatesabout, the heat picked up by the matrix from the hot fluid is conveyedby thel rotating matrix to the cold fluid. In preheaters prior to thisinvention, as far as is known, the inlet cross-sectional area and theoutlet crosssectional area of each of the ducts are equal. As iswellknown, when a fluid is heated, it expands thereby increasing itsspecific volume. Likewise, when a gas is cooled, it contracts with aresulting decrease in specific volume. Obviously in a preheater, changesin the specic volume of both fluids is continuously taking place. Theresult of changing specific volumes of both the hot fluid and the coldfluid in preheaters prior to this invention has been that as the tluidspass through a preheater, the velocity of llow of the uids is constantlychanging. Such changes in velocity result in large energy lossesrequiring that the fans used to force the iiuids through the preheatershave added capacity.

By way of this invention, the outer surface of a ringshaped rotarymatrix of a preheater can be divided into sectors representing equalarcs on the outside cylindrical surface. The same sectors result inequal arcs on the inside cylindrical surface. Obviously, the length ofthe arc on the inner surface is not as long as the arc on the outersurface, meaning that the sectors of the ring-shaped matrix convergetoward the center ofl the cylindrical matrix. By diverging the top andbottom of the matrix toward the center, it is possible to compensate thedecrease in dimension in one plane by an increase in dimension in theperpendicular plane,l thereby maintaining a constant cross-sectionalarea of passageway through each section of the matrix. In this way, asthe tluid flows through the matrix and into the inner chamber within thematrix, it tlows through a passageway encompassing a number of sections,each section having a constant crosssectional area from the outersurface to the inner surface. By passing the fluid back through thematrix at an angle rather than at a straight line, it is also possibleto use either a larger number of sections on the matrix or a smallernumber, thereby either increasing or decreasing the cross-section areathrough the matrix depending upon the change in specific volume of thefluid. In this way the area through which the uid passes when it leavesthe matrix may be made proportional to the change in specic volume ofthe iiuid caused by the quantity of heat either added to a removal fromthe fluid. If the fluid is cooled, -a smaller cross-sectional area isprovided for the outlet pass through the matrix as compared to the inletMice pass through the matrix. if the uid is heated, a largercross-sectional area is provided. In this way an approximately constantvelocity yflow is provided for the fluids resulting in reduced iiowlosses and increased efliciency.

Another source of loss in air preheaters has been the escape of fluidsfrom around the matrix of the -preheater. By means of circumferentialseals and radial seals which expand and contract with the expansion andcontraction and movement of the rotating air preheater, it is possibleto overcome such losses.

It is therefore an object of this invention to provide a preheater ofimproved economy and efficiency.

It is another object of this invention to provide a preheater withapproximately constant velocity of ow for each uid passing through thepreheater.

It is still another object of this invention to provide a preheater withminimum loss of fluids from around the matrix of the preheater.

It is still a further object of this invention to provide a preheaterrequiring minimum energy to force the fluids through the preheater.

Other objects and a fuller understanding of the vinvention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying rawings in which:

FIGURE l is a partly broken plan sectional view of a preheater embodyingthe present invention and taken along line 1 1 of FIGURE 2.

FIGURE 24 is a vertical section of a preheater taken along line 2-2 ofFIGURE l.

FGURE 3 is an venlarged detail illustrating the relationship of a radialseal to the inner and outer surfaces of the revolving matrix.

FIGURE 4 is an enlarged detail illustrating means for engaging acircumferential seal.

FIGURE 5 is an enlarged cross-section taken along the lines 5-5 ofFIGURE 4.

FIGURE 6 is an enlarged cross-section taken along the lines 6-6 ofFIGURE 4.

Referring now the drawings and more particularly to FIGURE l, theoutside housing 2l has a first inlet port 22 which introduces a hot uidsuch `as tiue gas from a source (not shown). A first outlet port 23removes the ue gas after it has passed through the air preheater to astock (not shown) or other suitable place for removal. A second inletport 2li introduces a cold huid such as combustion air from a source(not shown) to the preheater. Following the heating of the air, itpasses through the second outlet port 26 for use for example in afurnace (not shown) or other device, requiring heated air. In apreheater of this type a matrix 27 is used to convey the heat from thehot fluid to the cold liuid. As best seen in FIGURE 2, the matrix 27 issupported by an interior shell 28. The interior shell 28 is mounted on avertical post 29 by means of bearings itl for rotation. A top 30 andbottom 3l of the interior shell 23 enclose the matrix at these levels. Amotor 32 'with a pinion 33 drives a ring gear 34 used to rotate theinner shell 2S and matrix 27 about the vertical axis of the post 29.During the rotation of the matrix 27, heat is extracted from the hotfluid and transferred to the cold fluid.

It is preferable to form the matrix 27 in sector portions 25. In thisway a sector portion 25 `can be inserted into the matrix 27 through :anopening (not shown) in the top 30. The matrix 27 is designed in 4theform of a ring having an outer circumferential surface 39 yand an innercircumferential surface 41. Preferably, .the sector porltions 25 areequivalent. Disposed within each sector 25 are regenerative element-s'35.v Each element 36 is placed radially relative to the axis of thepost `29 and is composed of a material suitable for storing heat. innerends Yber 47,.

STOf'theregeherative lelements 36 lief along the inner surface 41. Outerends 38 CofV the regenerative ele1nents.- 36 lie` along the youtersurface G9. `The crossfsectional area formed by-the tvv-o adjacentregenerative .elements 36 andthe top 3d and botto-rn 31 represents -asepara-te;l Y' passageway 2@ for fluid flow. Y

In a plane perpendicular to Vthewcenter'line of the, posta,VY

' 39, as isV best shown in FIGURELeach sector portionZS converges to asmaller' and smallerV distance at-the inner.

" surface 41. The sector'portions 25 :are radially enclosed by Vsheets42.' As is best shown in FIGURE 2,the't0p Y baffle 36 and bottom baffle31v of the matrix Z7, however, are conically formed .so -asto divergefarther `and'fartherapart at the inner surface di. In this way as eachpassagevtfay 2l.) diverges in one plane to a smaller dimension, itconverges in a perpendicular plane to a smaller vdirnenvon whethery thej elastic Vseal-sp;areequually:as suitablei.-

sion, thereby maintaining a constant total cross-sectional w Varea ateach point ineach passageway 2th. In this way, as I Y a iiuid passesthrough the matrix 27, there is no change in the velocity of flow. Asgases arecooled, they contract and increase in den-V sity 'and thereforehave a smaller-.specific volume.V When heated,v gas expands therebyhaving a larger specific; iV

volume. Y fluid is beingy removed from thematrix as whenV 1t is beingintroduced into the,rnatrlix,.the, cross-section area of a passagewayfor flow must be through; the matrix v ifiby If the same.velocity offlow is. to exist when a changing ythe number of Vpassageways 2dthroughthe t 4matrix Z7v proportionately to the change inspeciflcVVolume. ArsV is Vshown in FG-.URE ,1,fthe cross-sectional area ,of .thefirst inletv ductgZrZ-and therfpassageway 2d `associated therewith issubstantially larger than Vthe crosssectional area of the iirstoutletduct Z3 .and the passage,- Ways 26 associated therewith. ltrisobvious, therefore,

that the first .inlet duct and the `rst outlet duct would .l

be used for the hot uid suchy as flue gas. The hot nuev.' Y

' gas .would enter .through the iirst inlet ductY 22 which gis-1eomparativelylarge at the time `when the flue gas has a very largespeciic volume `and low density. rfhe rst inletk duct 22 is associatedwith; a comparatively large j.

number of passageways Zd'through the matrix 27.V AS,`

the flu'evgasv passesthrough the passageways ,20, it be;`

. comes cooled rand reduces in specific volume. Due toV the decrease inspecificgvolume, a smaller cross-sectional area is lrequired to removethe gases through the matrix at the same velocity with`which they wereintroduced i through .the matrix. For this reason, the first outletducty i Z3 also has a `smaller cross-sectional area.

The Isecond inlet duct 24, which introduces cool fluid into thepreheaten'has a smaller cross-seotionalVa-rea than that of 'the secondAoutlet duct 26 through Vwhich'the heated fluid is discharged.` Y

The sequence of vinlet and outlet ducts here shown providesfor -atWo-pass,counterow heatfexchange rela- Y TheV matrix 27' rotates fromsaidlsecond inlet to said first outlet,

tionshi-p between the hot gas vand the cold gas.

lfrornsaid first outlet ductj to said first inletV duct 22,

from said flrstfinlet duct 2,2 to said secondoutlet duct26 `and fromsaidsecond outlet duct ,26 vback to said-lirst inlet i ductk 2A Withinthev inner surface Ilof `the matrix 27visga chamber 47 vwhich is dividedby a partition 28 into -a first Vcompartment:49 and a second compartmentSi. As best shown in FGURE'Z, plates 45 secured to shaft 29 pro-A vide,sealing for the Ytop and bottom of the axial. cham- Radial seals 54, ashestshown in FIGURES l and?, are

placed Vbetween the ends of the partitionl @and the inner" i surface 41and between theroutside housing21 and matrix 27.' The radial seals 54used in'association with the innerV surface 4d prevent leak-age -aboutthe partition48 while the radial seals Seis-associated with an outersurface 39); Y

ofV thematrix 2.7 prevent leakage betweenrtwo adjacent' ductsCurvedsurfaces 61 with' sliding protrusi-ons 56 are provided on theradialj seals 54 forislidving association n with the; matrix27g.Theshape of .thesurfacel depends Circumferentiallips `63 Vivhich protudeVvfromfthe-,top` 39' and thebottor'r'lilsl of the `shell 28'are`inSlidingycntact Y. with `circurnfrerentialtsealsol;'The'.circurnferential:seals f 64 are held inslidingcontact withthe'lipvwbyme'ansof g springs 65 (FIG. 4) reachingbetween fixed bar Zand'extension'l73'l The fixed bar72yis'securedto'theshousingg 21; The"spring :65 is mounted on rodhair/mehv sli'd'eablykr V.engagesextensionLI Thecircumferentialjseals 64 "asti shown'inFIGURE14fareheld'againsttheoutsidethousing .21 by springs fand 69;' .Therod-Visthreadedto the;V bracket 59.'andthe rod"7 6'V is threadedtothe@bracket 661, Y An extension 77 'on the Yseal 'gdghas anfenlargedslotE9?? to permit tangential movement .of-thef-sealed?` The roLinnercylindricalsurfacer l Althoughthe invention has beendescribedwitliacertain degree ofiparticularly, it is understoodl that theprese.VV entdisclosure has been made onlyj-bywayiof example;

andthatiuimerous changes 1in. the details of'construction and thecombination and garrangerne'irtV ofparts may bere-V l sorted to withoutdeparting from the spirit-and '.s'copeof v the inventionaslhereinafterrclaimed.`V I Y Y Y What i is vclaimed is:

l. Aregenerativefpreheater.forithefexchangeof-heat, i

betweenV a rst fluid and 'a second uidfcomprising:

Y a ring-shapedY permeable matrix Vhaving .anf inner, sur-l faceY and anputerv ,surfacev with equallyspacedregen Y VVerativeele'ments radiallyVplaced between said surrfarfses so as to formaradial passageway betweensaidV eleai@ ments, said'elements beingdiver'gently shapedso that the;cross-sectionalarea .of the passageway .between two contiguousregenerative elements Vrfe'rnairis'- approximately .constant as theelements radially con-r:v

Y verse, enclosing means -a shaft supporting said.'matrix,v i

ing radial'seals"andcircumferential seals,

a partition withinthe, space idefinedifby said innmerglsur'rfiVv y Yface forseparatiiig said` space-,into arfrs/t compart lment Vand asecond Cupartrnenn; i .Y y Y a first .inletgductdefiningacrossfsectionalvarea oflpassageway radially-inward *for introducinga'firstuid Y throughsaid `matrix into Vsaid first compartment;

menta passageway radially inward"fergintroducinga secondV Y Y fluidthrough said matrixY into said .second-'co-mpart-'j ment, 1

a second outlet ,duct defining a` cross-sectionalflarea ofpassagewayradially` outward forfrenioving said sec- L f' ond uid throughsaid matrix from said second com? v partment', land. 1

' means'forcontinuously rotating said matrix about said supporting shaftsothatsaid matrix AVpasses frornthe inlet ofcone fluid to thcrOutletoftheother uidif surface lcontactstheinner surface elif. 5 -or the.Vouter surface 39f`of Vthe-matrix 2X7'. {'Spr'ings'd' f' :held within:channels 5 5 force the vsur-face ,61against'the;z i 'Y matrix. Thesprings elproviderforce for a positive'seal. i wh-ile stillprovidingsuicienttelasticity tofcompensatejfor g expansionand'ontractionandirregularities'inthe matrix V- ,y Y27. Itis to beunderstood, however;ithatjothertypes of 1V for. preventing. the' escapev off fluid te the outside atmosphere, said enclosing means includatirst'outletlduct defining. cross-sectional ,areao'f passaugeway4radially outward for removing saidiifr'st,I fluidthrough said matrixlfrom said ir'stQcompartf arseco'nd inletduct fdeiiningV a`xcrosssectional area of?" 2. A regenerative preheater for the exchangeof heat between a hot fluid anda cold iiuid comprising:

a ring-shaped permeable matrix having an inner surface and anoutersurface with equally-spaced regenerative elements radially placedbetween said surfaces so as to form a radial passageway between saidelements, said elements being divergently shaped so that thecross-sectional area of the passageway between two contiguousregenerative elements remains approximately constant as the elementsradially converge,

an outside housing surrounding said matrix,

a shaft supporting said matrix,

a partition within the space defined by said inner surface forseparating said space into a first compartment and a second compartment,

a first inlet duct defining a cross-sectional area of passagewayradially inward for introducing a hot fiuid through said matrix intosaid first compartment,

a first outlet duct defining a cross-sectional area of passagewayradially outward for removing the hot fluid through said matrix fromsaid first compartment, the first outlet cross-sectional area beingsufficientlyrsmaller than the first inlet cross-sectional area tocompensate for the decrease in specific Volurne of the hot fluid causedby the cooling effect of the matrix,

a second inlet duct defining a cross-sectional area of passagewayradially inward for introducing a cold fluid through said matrix intosaid second compartment,

a second outlet duct defining a cross-sectional area of passagewayradially outward for removing the cold fluid from said secondcompartment through said matrix, the second outlet cross-sectional areabeing sufhciently larger than the second inlet cross-sectional area tocompensate for the increase in specific volume of the cold uid caused bythe heating effect of the matrix,

an inner housing enclosing the top and bottom of said rotating matrix,said inner housing having inner and outer sealing lips,

plates enclosing the top and bottom of the space defined by the innersurface ci said matrix,

outside radial seals located between each duct to prevent leakage aroundthe matrix within said outside housing,

inside radial seals located at the ends of said partition to preventleakage about said partition,

inner circumferential seals including bands in sliding relation withsaid inner scaling lips,

springs for forcing said inner circumferential seals against said lip,

springs for forcing said inner circumferential seals .against saidenclosing plates,

outside circumferential seals including bands in sliding yrelation withsaid outside sealing lips,

springs for forcing said bands against said outside sealings lips,

springs for forcing said outside circumferential seals against saidoutside housing, and

means for continuously rotating said matrix about said supporting shaftin a direction from said second inlet to said first outlet, from saidfirst outlet to said first inlet, from said first inlet to said secondoutlet, and from said second outlet back to said first inlet.

3. A regenerative preheater according to claim 2 wherein the first inletduct and first outlet duct are at an angle to one another and the secondinlet duct and second outlet duct1 are at an angle to one another.

References Cited by the Examiner UNITED STATES PATENTS 2,631,870 3/53Hodson 165-9 FOREIGN PATENTS 982,174 1/ 51 France.

OTHER REFERENCES Daimler-Benz, Germany printed application No. 1,121,-

CHARLES SUKALO, Primary Examiner.

1. A REGENERATIVE PREHEATER FOR THE EXCHANGE OF HEAT BETWEEN A FIRSTFLUID AND A SECOND FLUID COMPRISING: A RING-SHAPED PERMEABLE MATRIXHAVING AN INNER SURFACE AND AN OUTER SURFACE WITH EQUALLY-SPACEDREGENERATIVE ELEMENTS RADIALLY PLACED BETWEEN SAID SURFACES SO AS TOFORM A RADIAL PASSAGEWAY BETWEEN SAID ELEMENTS, SAID ELEMETNS BEINGDIVERGENTLY SHAPED SO THAT THE CROSS-SECTIONAL AREA OF THE PASSAGEWAYBETWEEN TWO CONTIGUOUS REGENERATIVE ELEMETNS REMAINS APPROXIMATELYCONSTANT AS THE ELEMENTS RADIALLY CONVERGE, ENCLOSING MEANS FORPREVENTING THE ESCAPE OF FLUID TO THE OUTSIDE ATMOSPHERE, SAID ENCLOSINGMEANS INCLUDING RADIAL SEALS AND CIRCUMFERENTIAL SEALS, A SHAFTSUPPORTING SAID MATRIX, A PARTITION WITHIN THE SPACE DEFINED BY SAIDINNER SURFACE FOR SEPARATING SAID SPACE INTO A FIRST COMPARTMENT AND ASECOND COMPARTMENT, A FIRST INLET DUCT INWARD FOR INTRODUCING A FIRSTFLUID SAGEWEAY RADIALLY INWARD FOR INTRODUCING A FIRST FLUID THROUGHSAID MATRIX INTO SAID FIRST COMPARTMENT, A FIRST OUTLET DUCT DEFINING ACROSS-SECTIONAL AREA OF PAS SAGEWAY RADIALLY OUTWARD FOR REMOVING SAIDFIRST FLUID THROUGH SAID MATRIX FROM SAID FIRST COMPARTMENT, A SECONDINLET DUCT DEFINING A CROSS-SECTIONAL AREA OF PASSAGEWEAY RADIALLYINWARD FOR INTRODUCING A SECOND FLUID THROUGH SAID MATRIX FROM SAIDFIRST COMPARTMENT, A SECOND OUTLET DUCT DEFINING A CROSS SECTIONAL AREAOF PASSAGEWAY RADIALLY OUTWARD FOR REMOVING SAID SECOND FLUID THROUGHSAID MATRIX FROM SAID SECOND COMPARTMENT, AND MEANS FOR CONTINUOUSLYROTATING SAID MATRIX ABOUT SAID SUPPORTING SHAFT SO THAT SAID MATRIXPASSES FROM THE INLET OF ONE FLUID TO THE OUTLET OF THE OTHER FLUID.